Kamala Harris’ favorability among American voters rose significantly in the week since she declared she would run to replace Joe Biden as the Democratic nominee for president, an ABC News/Ipsos poll released Sunday shows, while Donald Trump's favor has fallen—as the race between Trump and Harris tightens since Biden dropped out.

The poll, which sampled 1,200 adults on Friday and Saturday with a margin of error of 3 percentage points, found Harris' overall favorability rose from 35% to 43% over an ABC News/Ipsos poll conducted over the same period a week earlier.

Trump, however, saw his favorability drop from 40% to 36% from the week before, which was measured soon after an assassination attempt at a Pennsylvania rally and during the Republican National Convention.

Harris' unfavorability rating dropped four points—from 46% to 42%—meaning slightly more Americans now view her positively, and Trump's slightly rose from 51% to 52%.

Both candidates also saw significant movement among independent voters: 44% of independents have a favorable view of Harris this week (up from 28%) and Trump's favorability in the group fell from 35% to 27%.

Some 48% of Americans said they would be enthusiastic if Harris wins the Democratic nomination for president, while 39% say they are enthusiastic about Trump being the Republican nominee.

Harris and Trump have been virtually tied in recent polls with the race continuing to tighten—a major shakeup from just a week prior, when Trump appeared to open up a lead against Biden. A Wall Street Journal poll Friday with a 3.1-point margin of error showed Harris trailing Trump 47% to 49% and a HarrisX/Forbes online survey found 44% of voters have a favorable view of each candidate. In key swing states, Harris is trailing Trump by single-digit margins, new polls by Emerson College show. Trump leads Harris in Michigan, Georgia, Arizona and Pennsylvania with a virtual tie in Wisconsin.